The invention relates to a device according to the preamble of claim 1 or 3 and to a method of operating a device of this type.
In the case of a known device of this type (DE 299 02 149 U1) it is disclosed that the longitudinal duct is formed in the free end of the first piston rod. The air net which is connected to the longitudinal duct is not significant therein.
It is known per se from U.S. Pat. No. 4,927,444 A to attach the transfer mechanism to the piston rod of only one single pneumatic piston-cylinder unit. The longitudinal duct passes through the entire piston rod and the piston and issues into an advance chamber of the piston-cylinder unit. As shown in FIG. 1, the advance chamber can be selectively connected via a directional control valve to a first compressed air source of relatively low pressure or to a second compressed air source of relatively high pressure for the purpose of supplying the nozzles with blowing air. The disadvantage is that although in the case of the connection of the advance chamber to the first compressed air source the transfer mechanism is advanced slowly, but compressed air is also lost at the nozzles without being utilized. A further disadvantage is that when the directional control valve is in the other position the process of blowing air from the nozzles on to the glass containers is performed with substantial expenditure at the high compressed air pressure.
A piston-cylinder unit for linearly driving a pressing plunger of a press-and-blow glass forming machine, fixed to the piston rod, is known per se from DE 692 05 793 T2. The piston and the piston rod have an axial through bore for conducting cooling air to the pressing plunger. The free end of a cooling air pipe is sealingly extending into the through bore. The outer end of the cooling air pipe is attached to an end cap of the cylinder and is supplied with cooling air from a channel formed in said end cap.
It is known per se from U.S. Pat. No. 4,462,519 A to blow compressed air on to glass containers, which are placed on the dead plate in a row, by virtue of machine-fixed feeder nozzles such that each glass container is pushed into a corner of the transfer mechanism before it begins to pivot. The corners are oriented differently and can be advanced and then retracted independently of each other. Similar feeder nozzles are known per se from DE 198 00 080 C1.
It is known per se from U.S. Pat. No. 4,340,413 A, for the purpose of advancing and retracting the transfer mechanism to use two mutually parallel piston-cylinder units, whose piston rods are attached to the transfer mechanism.
DE 27 46 675 C2 illustrates details of the pivot drive and the pressure medium guidance and control for the purpose of advancing and retracting the transfer mechanism.
It is the object of the invention to improve the air conduction in the device and to reduce the consumption of compressed air.
This object is initially achieved by the device in accordance with claim 1. The dead plate is preferably perforated and cooling air can be controlled from below to pass through said dead plate. The second piston-cylinder unit only serves to advance the transfer mechanism to its outer end position. In contrast, the first piston-cylinder unit only serves to supply the nozzles with blowing air. In this manner, the blowing air in particular can only issue out of the nozzles in a precisely controlled manner, if this is required for the purpose of fixing the glass objects in the corners of the transfer mechanism during the pivoting transfer process. These features lead to a noticeable reduction in compressed air. A further advantage is that no disruptive blowing air is located in the comers as long as the glass objects are introduced into the corners.
By virtue of the features of claim 2, it is possible to retract the transfer mechanism in a rapid manner if the transfer mechanism has transferred the glass objects to the conveyor belt. Since the conveyor belt continues to run at a constant speed, it is necessary to obviate collisions of the pushing fingers with the transferred glass objects. The features of claim 2 serve this purpose.
The previously mentioned object is also achieved by virtue of the features of claim 3. The telescopic pipe represents a cost-effective way of supplying the nozzles with blowing air. The telescopic pipe can be accessed from the outside and can be monitored in this manner conveniently and can be maintained and replaced as required.
In accordance with claim 4, the transfer mechanism can be advanced to its outer end position in an advantageous, relatively slow manner. As a consequence, in the same manner as in claim 1 the transfer mechanism is not advanced too rapidly to its outer end position. As the transfer mechanism is being advanced, this prevents it from colliding with the glass objects which are to be transferred at a later stage. Whilst being advanced, the glass objects can still be suspended on a takeout device which transports the glass objects from the glassware forming machine on to the dead plate. During this procedure, any contact between the transfer mechanism and glass objects to be set down is to be obviated.
In turn, the features of claim 5 cause the transfer mechanism to be retracted to its inner starting position in an undesirably rapid manner.
The features of claim 6 are particularly advantageous in a structural sense.
In accordance with claim 7, an adjustable and precise path limitation is provided in a convenient manner for the transfer mechanism.
In accordance with claim 8, feeder nozzles are used if the glass containers which are set down on the dead plate are still disposed too far from the comers of the transfer mechanism located in its outer end position. In this case, the glass objects can be initially moved by the feeder nozzles into the corners, before the nozzles of the corners take on the function of fixing the glass objects in the corners. The fourth directional control valve can be formed as a 2 port/2 position valve.
In accordance with claim 9, the glass objects are set in rotational movement by virtue of the feeder nozzles and are introduced in a particularly protective and careful manner into the corners. The glass containers are prevented from being drawn by air in an undesirable manner in the direction of the feeder nozzles.
The features of claim 10 enable the supply of compressed air to the individual consumers to be adjusted in a sensitive manner such that the operation is performed in an optimum manner.
The previously mentioned object is also achieved by virtue of the method features of claim 11. This also serves noticeably to reduce the quantity of compressed air. As the glass objects are being introduced into the corners, there is no disruptive blowing air at this site. The first directional control valve can be formed e.g. as a 2 port/2 position valve. The first directional control valve can supply compressed air to the nozzles shortly before the transfer mechanism begins to pivot. This ensures that the glass objects are held in each case in a reliable manner in their corners of the transfer mechanism.
In accordance with claim 12, the glass objects can initially be moved into the corners by the action of the feeder nozzles, before the nozzles at this site serve to fix the glass objects in the corners.